A heating cooker where a timer period is increased whenever a timer key is pushed has been disclosed in Japanese Patent No. 3264235.
The heating cooker in the conventional art will be described with reference to FIGS. 8 to 10. FIG. 8 is a block diagram showing the structure of a heating cooker in the conventional art. FIG. 9 is a flowchart illustrating the operation when the long-push of a timer key in the conventional art is continued. FIG. 10 is a view showing indication examples of a timer period indicator.
In FIG. 8, a heating device 2 includes a heating coil 3 for inductively heating a pan or the like and an inverter circuit 4 for supplying high-frequency current to heating coil 3, and is connected to a commercial power supply 1. A control device 5 receives signals from an operation device 6, and controls inverter circuit 4 so that heating power corresponding to eight stages of “WEAK” to “STRONG” is applied to the pan. A timer period indicator 7 indicates a timer period or a remaining time, and is formed of LEDs or LCD. A heating power indicator 8 is formed of LEDs. Operation device 6 includes a timer period indicator 7, a heating power indicator 8, a down key 9, an up key 10, a heating off/on key 11, a timer key 12, and a timer cancel key 13.
The operation of the heating cooker will be described below. First, a user pushes heating off/on key 11 in order to perform heating. Subsequently, a signal is sent from operation device 6 to control device 5 so that set heating power becomes “5”. In this case, control device 5 controls inverter circuit 4, and the LEDs of heating power indicator 8 that correspond to the heating power of “WEAK” to “5” are turned on. The heating power of “WEAK”, “1”, “2”, “3”, “4”, “5”, “6”, and “STRONG” is set to about 120 W, about 235 W, about 370 W, about 500 W, about 700 W, about 1000 W, about 1450 W, and about 2000 W, respectively. The heating power can be changed into any heating power by using down key 9 or up key 10, and heating power is indicated on heating power indicator 8 so as to correspond to the change of the heating power. When the heating is terminated, the user pushes heating off/on key 11 again.
When the user intends to automatically stop the heating by timer heating after a set time, the user sets the timer. When timer key 12 is pushed, a timer period is indicated on timer period indicator 7. Whenever timer key 12 is pushed, the timer period is increased. Accordingly, it is possible to set the timer period to 9 hours and 30 minutes to the maximum extent.
In general, when each of the keys is pushed for 0.1 second, the push of the key is perceived. However, when the key is pushed for 0.1 second or more, the push of the key is perceived as along-push. Only timer key 12 is to be operated continuously. (For example, even though a user pushes up key 10 for a long time, the heating power is increased only by one stage.) When the long-push of timer key 12 is detected, the timer period is increased at intervals of 0.2 second. The timer can be set regardless of whether the heating is performed.
The operation when the long-push of timer key 12 is continued will be described below with reference to FIG. 9. When timer key 12 is pushed (Step 200), a timer mode starts and timer period indicator 7 indicates 1 minute as a timer period (Step 201). If it is determined that timer key 12 is still continuously pushed after that (Yes) (Step 202), control device 5 determines whether the timer period is the maximum time (Step 203). If the timer period is maximal (Yes), “ - - - ” is set (Step 204), “ - - - ” is indicated (Step 207), and the flow returns to Step 202. If the timer period is not maximal in Step 203 (No), it is determined whether the timer period is “ - - - ” (Step 205). If the timer period is “ - - - ” (Yes), the flow returns to Step 201. If the timer period is not “ - - - ” (No), the current timer period is increased (Step 206) and timer period indicator 7 indicates the time (Step 207).
When the timer period is increased, there is little point in the difference of the set timer period of 5 or 10 minutes. The increase of the timer period in step 206 is set to an interval of 1 minute for 1 to 20 minutes, an interval of 5 minutes for 20 minutes to 1 hour, an interval of 10 minutes for 1 to 3 hours, and an interval of 30 minutes for 3 hours to 9 hours and 30 minutes.
When the above-mentioned flow is repeated, the indication shown in FIG. 10 is indicated on timer period indicator 7. However, according to the above-mentioned heating cooker in the conventional art, when the timer key is the long-push state due to the failure or malfunction of the timer key, the indication of the set timer period is repeated from zero to the maximum time of a settable time, that is, 9 hours and 30 minutes. Alternatively, the set timer period is changed into an undesired time.
In a case where the timer key is not a mechanical switch but an electrostatic capacity type touch key, the timer key may be in the long-push state when a switch unit is smeared with water or foreign substances.